Loom dobby



- J6 se r Dec. 28, 1937. E HOLMES 2,103,784

LOOM DOBBY Filed Dec. 21, 1936 MMEM Patented Dec. 28, 1937 V UNITED STATES FATE-T OFEQE LOOM BOBBY Application December 21, 1936, Serial No. 116,975

6 Claims.

This invention relates to dobbies used for selecting and shifting harnesses in multi-harness looms. These harnesses are arranged in closely parallel relation but are necessarily positioned 5 at substantially different distances from the fell of the cloth, particularly when a considerable number of harnesses,-such as twenty, are used.

Consequently the rear harnesses must be given a substantially greater lift than the front harnesses to effect equalshed openings.

Upper and lower dobby hooks are connected through dobby back levers to the harness jacks and these hooks are selectively engaged and actuated by upper and lower dobby knives. It has been customary to operate these knives in such -manner that the rear end portion of each knife, which engages the hooks for the back harnesses, would have a greater=and more rapid travel than the front portion, which engages the hooks for :the front harnesses,

As a result, the knives have been obliquely inclined in one direction when they engaged the hooks, have been substantially perpendicular to the path of travelof the hooks at mid-stroke, and have been again obliquely inclined but in the opposite direction at the end of the lifting stroke. The spacing of the points of contact of the hooks along the knives has thus been constantly and reversely varied, so that relative sliding motions have taken place between the knives and the hooks while these parts were under substantial load. These relative sliding motions have caused substantial wear between the parts and have also caused substantial lateral strains on the hooks and associated parts. I

It is the object of my invention to provide an improved construction in a dobby, by which the desired diversity of harness lift may be effected by knives which remain perpendicular to the paths of travel of the hooks throughout their whole strokes, with all working positions of the knives substantially parallel.

To the accomplishment of this object, I preferably provide harness jacks of different proportions and leverage. A further important feature of my invention relates to the provision of an improved and novel supporting and bearing structure for the diiferently proportioned harness jacks.

My invention further relates to arrangements and combinations of parts which will be hereinafter described and. more particularly pointed out in the appended claims.

A preferred form of the invention is shown in the drawing, in which Fig, 1 is a sectional side elevation of portions of a loom dobby embodying my improvements; Fig. '2 is a sectional end elevation, taken along the line 22 in Fig. 1; and

Fig. 3 is a side elevation of certain parts to be described. 7

Referring to Fig. 1, I have shown a plurality of harness jacks ill, ll, 12, I3 and 14, several jacks of each kind being commonly provided. In Fig. 2 I have indicated four jacks I9 and a corresponding number of jacks H, i2, 13 and [4 may be assumed.

'Each harness jack is provided with a' dobby back lever 28, pivoted to its associated jack at '24 and having upper and lower dobby hooks 22 and Z3 pivoted thereto at the points 2t and 25.

The'levers 2t engage cross bars Zl which constitute stops to limit movement of the levers to the right in Fig. 1. The pivots 2| for all dobby -back levers are substantially aligned when the jacks are in lowered position.

The hooks 2'2 and 23 are positioned for engagement by an upper dobby knife 36 and by a lower dobby knife 3| respectively. These knives are alternately reciprocated by any suitable actuating mechanism, and are at all times substantially perpendicular (transversely) to the hooks 22 and 23 and to the paths of travel of the hooks.

The harness jacks ill to M are provided with end bearing portions or knobs 4% M, 42, 43 and s t respectively, which constitute centers for the swinging motion of the harness jacks. In order to provide supporting bearings for the knobs 40 to M, I use a series of bearing plates 5!), 5| and 52. Each of these plates is provided with a bearing notch 55 and with holes 56 to receive tierods or bolts 51 and 53 (Fig. 2). By reversing the plates 50 and 5! (Fig. 3), these three different kinds of plates 59, 5| and 52 may be combined to provide bearing notches 55 at the five different elevations indicated in Figs. 1 and 3. The bearing plates 56 provide bearing notches 55 for the harness jacks H) and l4,'the plates 5| provide bearing notches for the jacks II and I3, and the plates 52 provide bearing notches for the jacks l2. Separator plates 60 are mounted between the plates 5t, 5t and 52 to maintain the harness jacks in spaced and. operative position.

With a dobby thus constructed, all of the upper dobby hooks will be given equal travel and all of the lower dobby hooks will also be given equal travel. The pivots 2i in the harness jacks will thus all swing in arcs of equal length.

The difference in jack proportions and leverage is such, however, that the jacks ID will have the greatest swinging movement at the upper end where the harnesses are connected, and that the jacks M will have the least swinging movement. Consequently the jacks ID are to be connected to the back harnesses to give them the greatest lift, while the jacks M are to be connected to the front harnesses to give them the smallest lift, the other jacks being connected to intermediate harnesses in successive groups.

The necessary difference in lift to maintain theoretically equal shed opening is relatively small within each group, and the provision of equal lift for all of the harness jacks in each small group closely approximates equal shed opening. For closer adjustment, each jack is provided with the usual series of notches by which the lift of each harness may be further adjusted.

By my improved construction I retain the advantages of the old construction so far as substantially equal shed opening is concerned, while at the same time I avoid the oblique Working positions of the dobby knives and the resultant lateral strains and relative sliding movements between the knives and dobby hooks.

Having thus described my invention and the advantages thereof, I do not wish to be limited to the details herein disclosed, otherwise than asset forth in the claims, but what I claim is:

i. In a dobby, a plurality of harness jacks of difierent proportions and leverage, a dobby back lever pivoted to each jack, upper and lower dobby hooks for each lever, means to give said hooks and levers equal travel, and means to provide pivotal supporting bearings for said jacks at different but graduated distances from the points of pivotal connection between said jacks and said dobby back levers.

2. In a dobby, a plurality of harness jacks having lower end portions of different lengths and having the remaining portions substantially identical, and bearing means for said different end portions effective to support said jacks with the identical upper portions substantially at the same level.

3. In a dobby, a plurality of harness jacks having lower end portions of different lengths and having the remaining portions substantially identical, and bearing means for said different end portions effective to support said jacks with the identical upper portions substantially at the same level, said bearing means comprising bearing plates having notches at different distances from the ends thereof, and certain of said plates being reversible to coact with jacks of two different lengths.

4. A plurality of harness jacks, a pair of actuating dobby knives selectively connected to indicated jacks, and means to give all parts of each knife equal travel whereby all operative positions of each knife are parallel, said harness jacks being of such relative proportions and leverage that said defined movements of said knives will effect movements of said jacks which increase progressively toward the back of the loom.

5. In a dobby, a plurality of harness jacks, upper and lower dobby hooks, connected through dobby back levers to said harness jacks, and means to give every upper hook equal travel and every lower hook equal travel, said harness jacks being of such relative proportions and leverage that said equal movements of said hooks will effect movements of said jacks which increase progressively toward the back of the loom.

6. In a dobby, a plurality of harness jacks, a pair of actuating dobby knives selectively connected to indicated jacks, the engaging surface tion and leverage that said defined movements qo of said knives will effect movements of said jacks which increase progressively toward the back of the loom.

ELBRIDGE R. HOLMES. 

